Difference between revisions of "R-Car/Virtualization/VFIO"
< R-Car | Virtualization
(GPIO Pass-Through / Guest Side) |
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* Build and boot a host kernel using: | * Build and boot a host kernel using: | ||
− | ** Repository: | + | ** Repository: https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git |
** Branch: "topic/rcar3-virt-gpio-passthrough" | ** Branch: "topic/rcar3-virt-gpio-passthrough" | ||
** Config: "renesas_defconfig" | ** Config: "renesas_defconfig" | ||
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* Build a guest kernel using: | * Build a guest kernel using: | ||
− | ** Repository: | + | ** Repository: https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git |
** Branch: "topic/rcar3-virt-gpio-passthrough" | ** Branch: "topic/rcar3-virt-gpio-passthrough" | ||
** Config: "virt_defconfig" | ** Config: "virt_defconfig" |
Revision as of 06:31, 9 February 2018
Device Pass-Through Using VFIO
Platform Device Pass-Through Proof-of-Concept
This is a proof-of-concept showing how to provide guest access to an R-Car GPIO controller block on the Renesas Salvator-XS board.
Host Side
- Build and boot a host kernel using:
- Repository: https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git
- Branch: "topic/rcar3-virt-gpio-passthrough"
- Config: "renesas_defconfig"
- Configure workarounds for missing functionality:
$ echo 0 > /sys/module/vfio_platform/parameters/reset_required $ echo 1 > /sys/module/vfio/parameters/enable_unsafe_noiommu_mode
- Unbind GPIO6 from the "gpio-rcar" driver:
$ echo e6055400.gpio > /sys/bus/platform/drivers/gpio_rcar/unbind gpio gpiochip6: REMOVING GPIOCHIP WITH GPIOS STILL REQUESTED
- Bind GPIO6 to the "vfio-platform" driver, for pass-through to guests:
$ echo vfio-platform > /sys/bus/platform/devices/e6055400.gpio/driver_override $ echo e6055400.gpio > /sys/bus/platform/drivers/vfio-platform/bind iommu: Adding device e6055400.gpio to group 0 vfio-platform e6055400.gpio: Adding kernel taint for vfio-noiommu group on device
Guest Side
- Build a guest kernel using:
- Repository: https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git
- Branch: "topic/rcar3-virt-gpio-passthrough"
- Config: "virt_defconfig"
- Build QEMU using:
- Repository: https://github.com/geertu/qemu.git
- Branch: "TBD"
- When starting QEMU, specify pass-through of the GPIO6 platform device. The device specifier consists of three parts:
- $1a
- the device's node name, or
- $1b
- the full path to the device's node in sysfs,
- $2
- the manufacturer part of the device's compatible value,
- $3
- the model part of the device's compatible value.
I.e.:
-device vfio-platform,host=$1a,manufacturer=$2,model=$3 -device vfio-platform,host=e6055400.gpio,manufacturer=renesas,model=rcar-gen3-gpio -device vfio-platform,sysfsdev=$1b,manufacturer=$2,model=$3 -device vfio-platform,sysfsdev=/sys/bus/platform/devices/e6055400.gpio,manufacturer=renesas,model=rcar-gen3-gpio
Full command line:
$ qemu-system-aarch64 -enable-kvm -M virt -cpu cortex-a57 -m 1024 -nographic \ -kernel /path/to/guest/kernel/Image \ -device vfio-platform,host=e6055400.gpio,manufacturer=renesas,model=rcar-gen3-gpio
Host kernel output:
vfio-platform e6055400.gpio: no reset function found! vfio-platform e6055400.gpio: vfio-noiommu device opened by user (qemu-system-aar:3003)
Guest kernel output:
Booting Linux on physical CPU 0x0000000000 [0x411fd073] ... gpio_rcar c000000.e6055400.gpio: missing clock, ignoring gpio_rcar c000000.e6055400.gpio: missing IRQ, ignoring gpio_rcar c000000.e6055400.gpio: driving 32 GPIOs ...
- Analysis of "/sys/firmware/devicetree/base" using "dtx_diff" shows that "e6055400.gpio@0" has been added as a subnode to the existing "platform@c000000" node:
--- /sys/firmware/devicetree/base.orig +++ /sys/firmware/devicetree/base @@ -124,6 +124,13 @@ compatible = "qemu,platform", "simple-bus"; interrupt-parent = <0x8001>; ranges = <0x0 0x0 0xc000000 0x2000000>; + + e6055400.gpio@0 { + #gpio-cells = <0x2>; + compatible = "renesas,rcar-gen3-gpio"; + gpio-controller; + reg = <0x0 0x50>; + }; }; pmu {
- Export GPIOs used for LEDs, and turn all LEDs off:
base=$(cat /sys/class/gpio/gpiochip*/base) for i in $(seq 11 13); do echo $(($base + $i)) > /sys/class/gpio/export echo low > /sys/class/gpio/gpio$(($base + $i))/direction done
- Cycle through all LEDs, letting them blink once:
for i in $(seq 11 13); do echo high > /sys/class/gpio/gpio$(($base + $i))/direction sleep 1 echo low > /sys/class/gpio/gpio$(($base + $i))/direction done